Speaker
Description
Cosmic rays below a few hundred GeV and solar energetic particles are key to understanding how the Sun is interacting with its own solar system, as they respond to the magnetic field that fills the entire Heliosphere, not only during quiet times, but also during episodes of solar activity, as they change the propagation conditions of cosmic rays and solar energetic particles through the Heliosphere. Direct observations of these two types of energetic particles can be made in space using detectors aboard spacecraft such as the Energetic Particle Detector aboard the Solar Orbiter and/or the AMS aboard the International Space Station, for example, and indirect observations using ground-based detectors such as neutron monitors and muon telescopes that measure secondary particles produced through the interaction between cosmic rays and solar energetic particles with atmospheric nuclei.
An ideal ground-based detector to investigate the solar-terrestrial relationship should provide the flux of energetic particles, their energy, their identity and their spatial distribution. Neutron monitors and muon telescopes are the usual instruments for this purpose. Neutron monitors can give the neutron count rate although they may have some response to protons and muons. Although direct measurement of the energy/rigidity of energetic particles is not possible, the combination of several neutron monitor stations at different geomagnetic latitudes can provide a spectrum for these particles and the isotropy of energetic particles in the sky. A rough estimate of this energy can also be provided by a single neutron monitor if it can detect multiplicities by recording the time between successive neutron detections or by capturing height pulses. Muon telescopes provide count rates of charged particles, mainly muons, entering the detector; their configuration usually allows estimation of incoming particle directions and a better estimate can be achieved if several geographically well separated muon telescopes are used. However, due to the energy threshold for muon production, these detectors are less sensitive to solar energetic particles than neutron monitors. In recent years, our group has developed and deployed a type of detectors that can provide both neutron and muon count rates, some information about the cosmic and solar particle spectra, and the arrival directions of muons in the detector volume. This is a combination of a neutron monitor and a muon telescope that share the same structure. At the moment, one of them is operating at the Spanish Antarctic Base Juan Carlos I and a second one is operating at the Izaña Observatory, on the slope of Mount Teide, on the island of Tenerife. We present our ground based detectors, including our first neutron monitor, CaLMa, and our minineutron monitor, miniCaLMa, a multipurpose neutron monitor, as well as our latest results on solar events and the response of neutron monitors as a function of altitude.
