BEXCO - Room F(201/202/203/204)
[SH070] The energetic particle flux estimated from cosmogenic isotopes produced in lunar samples
Direct measurements of solar energetic particles (SEP) became possible only in the space era covering past several decades. However, for many academic and practical reasons, it is important to know the SEP flux on much longer time scales in the past. Such information can be obtained using reconstructions based on cosmogenic radioisotope measurements in objects without magnetic and atmospheric shielding such as lunar surface or meteoroids. Thanks to the Apollo missions, samples of lunar rocks have been brought to the Earth and measured for the isotope content. Although estimates of the average SEP flux from cosmogenic radionuclides measured in lunar samples have been made earlier, here we revisit the approach using newly calculated depth profiles of yield functions for Be-10, C-14, Al-26 and Cl-36 in lunar rocks. We have developed a full Monte-Carlo model of the nuclide production by energetic particles in the rock. As a result, we present the improved estimate of the average solar energetic particle flux at 1 AU on the multi-millenial time scales.