| Journal: | Brazilian journal of physics |
| Database: | PERIÓDICA |
| System number: | 000398971 |
| ISSN: | 0103-9733 |
| Authors: | Szadkowski, Zbigniew1 Szadkowska, Anna2 |
| Institutions: | 1University of Lodz, Department of Physics and Applied Informatics, Lodz. Polonia 2Lodz University of Technology, Center of Mathematics and Physics, Lodz. Polonia |
| Year: | 2014 |
| Season: | Dic |
| Volumen: | 44 |
| Number: | 6 |
| Pages: | 805-810 |
| Country: | Brasil |
| Language: | Inglés |
| Document type: | Artículo |
| Approach: | Analítico |
| English abstract | Experiments which show coherent radio emission from extensive air showers induced by ultra-high-energy cosmic rays are designed for a detailed study of the development of the electromagnetic part of air showers. Radio detectors can operate with 100 % up time as, e.g., surface detectors based on water-Cherenkov tanks. They are being developed for ground-based experiments (e.g., the Pierre Auger Observatory) as another type of air-shower detector in addition to fluorescence detectors, which operate with only ∼10 % of duty on dark nights. The radio signals from air showers are caused by coherent emission from geomagnetic radiation and charge-excess processes. The self-triggers in radio detectors currently in use often generate a dense stream of data, which is analyzed afterwards. Huge amounts of registered data require significant manpower for off-line analysis. Improvement of trigger efficiency is a relevant factor. The wavelet trigger, which investigates on-line the power of radio signals (∼ V 2/R), is promising; however, it requires some improvements with respect to current designs. In this work, Morlet wavelets with various scaling factors were used for an analysis of real data from the Auger Engineering Radio Array and for optimization of the utilization of the resources in an FPGA. The wavelet analysis showed that the power of events is concentrated mostly in a limited range of the frequency spectrum (consistent with a range imposed by the input analog band-pass filter). However, we found several events with suspicious spectral characteristics, where the signal power is spread over the full band-width sampled by a 200 MHz digitizer with significant contribution of very high and very low frequencies. These events may not originate from cosmic ray showers but could be the result of human contamination. The engine of the wavelet analysis can be implemented in the modern powerful FPGAs and can remove suspicious ev |
| Disciplines: | Física y astronomía |
| Keyword: | Física de partículas y campos cuánticos, Rayos cósmicos, Radio detección |
| Keyword: | Physics and astronomy, Particle physics and quantum fields, Cosmic rays, Radio detection |
| Full text: | Texto completo (Ver PDF) |
