Initial concept for forecasting the flux and energy spectrum of energetic particles using ground-level cosmic ray observations

Abstract

We describe the principles and operation of automated programs “FEP-Research-1st Alert”, “FEP-Research-2nd Alert”, and “FEP-Research-3rd Alert”. The program “FEP-Research-lst Alert” gives preliminary determinations of the energy spectrum and flux at the beginning of an event on the basis of 1-minute data of total neutron intensity and intensities of different multiplicities in the neutron monitor (NM) at the Emilio Segre' Observatory (2025m above sea level, Rc = 10.8 GV) as well as available 1-minute on-line data in the near future of Cosmic Ray Observatories which collaborate with the Israel Cosmic Ray Center (Rome, Haleakala, Climax, Oulu, Moscow, Apatity, Mexico, Aragaz and others). Using well-known coupling functions for neutron monitors we have derived functions that relate the spectral index of flare energetic particles (FEP) to observations of multiplicities. We also derived important functions using ratios of FEP observations from the different cosmic ray monitors mentioned above. All these functions are approximated analytically with good accuracy and can be used for automatic realtime determination of the energy spectrum and fluxes of FEP. Using approximate values of the diffusion coefficient for the current level of solar activity as a function of particle energy, the program “FEP-Research-1st Alert” determines very roughly the expected level of radiation in space after 1 2 , 1, 3 2 and 2 hours. If this level is expected to be dangerous for satellites and spacecrafts, the program “FEP- Research-1st Alert” sends preliminary 1st Alert. More accurate forecasts are given after 5–10 minutes by the program “FEP-Research-2nd Alert”, and after 10–20 minutes program by the “FEP-Research-3rd Alert” using information on the diffusion coefficient obtained from on-line FEP ground data.