Speaker
Description
Particle acceleration inside the solar atmosphere remains not fully understood. Although several mechanisms have been proposed, a widely accepted framework is still lacking. Understanding these processes is crucial not only for studying particle acceleration itself but also for providing deeper insights into the solar explosive events. The most natural approach to studying particle acceleration mechanisms is by analysing the ionised particles that escape into the heliosphere, which may eventually reach the Earth. Additionally, a strong flux of these particles is emitted, facilitating their study. Nevertheless, the main drawback of this approach lies in the difficulty of precisely determining ionised particles' trajectories, as they are affected by the electromagnetic field present in the heliosphere.
Solar neutrons (SNs) are produced by the collisions between accelerated particles, mainly protons and $\alpha$, and nuclei present in the solar atmosphere. A portion of the kinetic energy of the former is transferred to the SNs, and as a result, some of them escape the solar atmosphere. Since SNs do not experience the Lorentz force, they propagate undisturbed through the magnetosphere, following a straight trajectory. This offers an alternative approach for analysing particle acceleration in the solar atmosphere, independent of the magnetosphere. At present there are no in situ instruments to detect SNs, but their relation to certain gamma emission lines makes it possible to detect their production. On the other hand, ground-based detectors such as neutron monitors could detect SNs themselves under special conditions.
In order to study SN production and propagation, certain challenges must be overcome. Firstly, SNs are produced by different collision processes. It is essential to calculate both the SN flux and its kinetic energy for all of these collisions, as well as their course within the solar atmosphere until their capture or escape. Secondly, the SN flux is much lower than that of ionised particles and much more sporadic. Additionally, the neutron mean lifetime (879 s) is not long enough for many of them to reach Earth, which further complicates their detection. Finally, both SNs and ionised particles induce similar Extensive Air Showers upon entering into the Earth's atmosphere thus, they are indistinguishable. For this reason, gamma-ray emission should be considered.
SN production has been simulated, taking into consideration various parameters concerning the solar atmosphere. These simulations involved not only the collisions but also the possible outcomes for the neutrons, which include being lost to the Sun's interior, capture with the subsequent emission of gamma-rays, or escaping. Finally, we evaluate the consequences of gamma-rays and escaping SNs on Earth, aiming to gain deeper insight into the solar atmosphere.
