Particle detectors in solar physics and space weather research

The use of large area particle detectors, which can only be accommodated on the Earth's surface, is vital for measuring the low fluxes of high energy particles accelerated in the vicinity of the Sun. The mystery of particle acceleration in the Universe cannot be explored without the understanding of solar particle accelerators. The energy spectra of highest energy solar particles, as measured by the surface detectors, will shed light on these universal processes of high-energy particle acceleration at numerous galactic and extragalactic sites. Detected at Earth, energetic particles also can provide extremely cost-effective information on the key characteristics of the interplanetary disturbances. Because cosmic rays are fast this information travels rapidly and can be useful for space weather forecasting. Taking into account that only very few of a great number of solar flares and coronal mass ejections (CME) produce intensive ion fluxes, the socalled solar energetic particle events, it is not only critical to alert clients about the arrival of the most severe radiation storms, but also to minimize the number of false alarms against events which are not severe enough to cause damage. Using examples of extreme solar events from the 23rd solar cycle, we present experimental results and analysis of the sensitivity of the secondary cosmic ray flux, registered at middle latitudes to the various parameters of the solar particle "beams" incident on the Earth's atmosphere. (c) 2007 Elsevier B.V. All rights reserved.