BEXCO - Room F(201/202/203/204)
[CRI141] Study of the LOFAR radio self-trigger and single-station acquisition mode
The LOw Frequency ARay (LOFAR) observatory is a multipurpose radio antenna array aimed to detect radio signals in the frequency range 10-240 MHz. Radio antennas are clustered into over 50 stations, and are spread along central and northern Europe, with a higher density in the northern Netherlands. The LOFAR core, where the density of stations is highest, has been used since 2011 for detecting radio-signals associated to cosmic-ray air showers in the energy range 10^16-10^18 eV. The collected data have been used for characterizing the geometry of the observed cascade in a detailed manner. Data acquisition of the radio-signal is triggered by the LOfar Radboud air shower Array (LORA), covering an area of about 300 m diameter centered at the LOFAR core position. The LORA scintillator array provides energy, arrival direction, and core position of the detected air shower. As drawback, also a small fraction of the LOFAR array is currently used for cosmic-ray detection. In order to increase the statistics of cosmic ray detection at high energy and to extend the cosmic-ray energy range, it is necessary to improve the effective collecting area to the whole LOFAR array. On this purpose, a detailed study about the LOFAR potentialities of working in self-trigger mode, i.e. with the cosmic-ray data acquisition trigger provided by the radio-antenna only, has been carried out. For this task, a RFI (Radio Frequency Interferences) rejection system has been developed too. Moreover, since the radio pattern at ground level is much smaller than the distance among stations far from the LOFAR core, a detailed study of the LOFAR performance in single-station mode has been carried out as well. Both studies and the implications for future high-energy cosmic-ray radio-detectors will be presented.