  We revisited assessments of the occurrence probability distribution of large
events in solar energetic particles (SEP), based on measurements of cosmogenic
radionuclides in lunar rocks. We present a combined cumulative occurrence
probability distribution of SEP events based on three time scales: directly
measured SEP fluences for the last 60 years; estimates based on terrestrial
cosmogenic radionuclides 10Be and 14C for the multi-millennial (Holocene) time
scale; and cosmogenic radionuclides measured in lunar rocks on the time scale
of up to 1 Myr. All the three time scales yield a consistent distribution. The
data suggest a strong rollover of the occurrence probability so that SEP events
with the fluence of protons with energy >30 MeV greater than 10^{11} (protons
/cm2/yr) are not expected at the Myr time scale.
